Electrophotographic image-forming devices that form images through a process of irradiating a laser beam onto a photosensitive member to form an electrostatic latent image thereon and depositing developer on the latent image are well known in the art. When rendering gradations, for example, this type of image-forming device often produces dots having no neighboring dots (i.e., isolated dots). Since isolated dots can lead to a decline in image quality due to skipped dots or the like, it is desirable to take measures to process these isolated dots. For example, Japanese unexamined patent application publication No. P2001-45299A proposes a technique for emphasizing isolated dots to an extent that does not affect nearby pixels.